Multi-stage receiver for multipath and interference suppression in multi-user CDMA

Abstract

Multipath fading in wireless CDMA systems worsens the effects of multiple access interference and also leads to the near-far problem. In this paper, a multi-stage receiver structure is considered for synchronous code division multiple access (S-CDMA) systems observed in multipath. The proposed receiver consists of conventional correlator detectors and matrix decision feedback filters. It is shown that the multipath channel and a bank of correlators in a multi-user CDMA environment can be modeled as a multi-input, multi-output FIR channel. This link between multi-user detection in direct sequence (DS) CDMA and FIR MIMO system identification problem which has been studied extensively in signal processing area enables the use of powerful signal processing techniques. Performance of the proposed receiver structure is studied via simulations.